The relationship between inner surface potential and electrokinetic potential from an experimental and theoretical point of view

2017 ◽  
Vol 14 (5) ◽  
pp. 295 ◽  
Author(s):  
Tajana Preočanin ◽  
Danijel Namjesnik ◽  
Matthew A. Brown ◽  
Johannes Lützenkirchen
Keyword(s):  
Surface Properties ◽  
Surface Potential ◽  
Single Particle ◽  
Surface Reactions ◽  
Solid Particles ◽  
Theoretical Point ◽  
Surface Characterisation ◽  
Layer Potential ◽  
Average Surface ◽  
Inner Surface

Environmental contextInterfacial properties of colloid and nanoparticles are directly related to the reactivity and surface densities of existing surface sites. Surface characterisation of particles provides only some kind of average surface properties. Analysis of well-defined monocrystal surfaces, which form the surface of the single particle, leads to a better understanding of surface reactions and mutual interactions of adjacent crystal planes on average surface properties. AbstractThe contact of small solid particles and macroscopic flat planes with aqueous electrolyte solutions results in the accumulation of ions at the interface and the formation of the electrical interfacial layer. Analysis of well-defined monocrystal surfaces, which are the building blocks of a single particle, leads to a better understanding of surface reactions and mutual interactions of adjacent crystal planes on average surface properties of particles. We analyse inner surface potential (obtained by single-crystal electrode) and zeta-potential data (obtained by streaming potential measurements) that were obtained on identical samples. Among the systems for which comparable surface and zetapotentials are available, measured inner surface potential data for sapphire (0001), haematite (0001) and rutile (110) show the expected behaviour based on the face-specific surface chemistry model, whereas the slopes for rutile (110) and quartz (0001) do not. Isoelectric points for sapphire (0001), haematite (0001) and rutile (100) are in conflict with the standard model that implies consistent behaviour of surface potential and diffuse layer potential. For the two former systems, previous results from the literature suggest that the charge of interfacial water can explain the discrepancy. The water layer could also play a role for quartz (0001), but in this case, the discrepancy would simply not be noticed, because both point of zero potential and isoelectric point are low. Along with data on silver halides, it can be concluded that six-ring water structures on solids may generate the electrokinetic behaviour that is typical of inert surfaces like Teflon.

scholarly journals Effect of Water Adsorption on Cation-Surface Interaction Energy in the Na-Mordenite of 5.5 : 1 Si/Al Ratio

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Sekou Diaby
Keyword(s):  
Activation Energy ◽  
Surface Properties ◽  
Surface Potential ◽  
Water Adsorption ◽  
Adsorbed Water ◽  
Material Surface ◽  
Water Molecules ◽  
Zeolite Surface ◽  
Inner Surface ◽  
Insight Into

The mobility of the Na+cations localized at the inner surface of the studied mordenite zeolite depends on the material surface properties. In this work, we show that the activation energy,ΔEhop, relating to the Na+cation hopping displacement is associated to the surface potential and therefore can be used to get a better insight into the zeolite surface properties. Indeed, when molecules as water are adsorbed at the surface, they modify the surface potential energy and hence influence the value ofΔEhop. If the adsorbed molecules are polar they directly interact with the cations which become more mobile. The more theΔEhopvalue is, the less the amount of adsorbed water molecules is. Alterations of theΔEhopvalue with respect to the amount of adsorbed water molecules are interpreted using the Dubinin model which is based on simple adsorption principle.

Numerical Simulation of Particulate Jet Generated by Free Falling Particles

2003 ◽  
Author(s):  
Tomomi Uchiyama
Keyword(s):  
Numerical Simulation ◽  
Particle Velocity ◽  
Single Particle ◽  
Maximum Velocity ◽  
Vortex Method ◽  
Solid Particles ◽  
Airflow Rate ◽  
Two Dimensional ◽  
Free Falling ◽  
Free Turbulent Flow

This paper is concerned with the numerical simulation of the particulate jet generated by solid particles falling from a slit orifice into an unbounded quiescent air. A two-dimensional vortex method, proposed for the analysis of particle-laden free turbulent flow in prior papers, is employed for the simulation. The falling particles induce complicated airflow involving eddies with a wide variety of scales. The air takes its maximum velocity at the jet centerline. The particle velocity is higher than the free falling velocity of a single particle. The effects of the diameter and density of the particle on the flow are investigated. The entrained airflow rate is favorably compared with the value predicted by an analytical model.

Synthesis and Langmuir Monolayer Characterisation of Some Nitro Derivatives of Polyphenyl Carboxylic Acids

2009 ◽  
Vol 2009 (4) ◽  
pp. 225-228 ◽  
Author(s):  
Patrycja Dynarowicz-Łątka ◽  
Piotr Milart
Keyword(s):  
Surface Potential ◽  
Langmuir Monolayers ◽  
Nitro Derivative ◽  
Hydrophobic Core ◽  
Carboxylic Group ◽  
Experimental Conditions ◽  
Layer Potential ◽  
Interface Surface ◽  
Hydrophobic Moiety ◽  
Derivatives Of

Derivatives of 5′-phenyl-1,1′:3′,1″-terphenyl-4-carboxylic acid (PTCA), each with 4′-nitro-substituents (2 and 5) have been synthesised and characterised as Langmuir monolayers at the air/water interface. Surface pressure and electric surface potential measurements of the monolayers under a variety of experimental conditions have been made. The presence of the nitro-substituent (in 2 cf 2′) was found to change the sign of the measured surface potential, indicating that the nitro-derivative is oriented with the -NO2 group towards the air side, while the carboxylic group is anchored into the water subphase. Upon introducing two more side phenyl groups into the hydrophobic core of the nitro derivative 2 to give 5, the measured surface potential (and the resulting apparent dipole moment) change sign to positive, indicating the prevalence of the dipolar contribution from the hydrophobic moiety over that of the hydrophilic part of the molecule. Our results show that the contribution of the double layer potential arising from ionisation of the carboxylic group of the investigated molecules is | 0.1 | V.

scholarly journals Effect of Rhamnolipids and Lipopolysaccharides on the Bioleaching of Arsenic-Bearing Waste

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1303
Author(s):  
Agnieszka Pawlowska ◽  
Zygmunt Sadowski ◽  
Katarzyna Winiarska
Keyword(s):  
Surface Properties ◽  
Extraction Efficiency ◽  
Solid Phase ◽  
Solid Particles ◽  
Metal Extraction ◽  
Arsenic Compounds ◽  
Glass Column ◽  
Microbial Leaching ◽  
Bacteria Adhesion ◽  
Leaching Efficiency

The adsorption of biosurfactants and polysaccharides changes the surface properties of solid particles, which is important for controlling the release of arsenic compounds from the solid phase and preventing undesirable bioleaching. Microbial leaching and scorodite adhesion experiments, including pure and modified mineral material, were conducted in a glass column with a mineral bed (0.8–1.2 mm particle size) to test how rhamnolipids (Rh) and lipopolysaccharides (LPS) affect surface properties of mineral waste from Złoty Stok (Poland) and secondary bio-extraction products (scorodite). Adsorption tests were conducted for both solid materials. The adsorption of Rh and LPS on the solids was shown to modify its surface charge, affecting bioleaching. The highest bio-extraction efficiency was achieved for arsenic waste with adsorbed rhamnolipids, while the lowest, for the LPS-modified mineral. Under acidic circumstances (pH~2.5), the strongly negative zeta potential of arsenic-bearing waste in the presence of Rh creates conditions for bacteria adhesion, leading to the intensification of metal extraction. The presence of a biopolymer on the As waste surface decreases leaching efficiency and favours the scorodite’s adhesion.

Importance of Accounting for Finite Particle Size in CFD-Based Erosion Prediction

2018 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Yongbo Wang
Keyword(s):  
Particle Size ◽  
Prediction Models ◽  
Jet Impingement ◽  
Point Particle ◽  
Solid Particles ◽  
Future Research ◽  
Theoretical Point ◽  
Slurry Flow ◽  
Erosion Prediction ◽  
Impact Erosion

Being capable in predicting the removal of material from a surface subjected to the impingements of solid particles within a carrier liquid is of considerable industrial interest. This phenomenon, called impact erosion, is of concern in many applications due to its severe technical and economic consequences. The use of Computational Fluid Dynamics (CFD) techniques for impact erosion prediction is a challenging approach to avoid the cost and complexity of laboratory testing. A well-established methodology exists for CFD-based erosion estimation, consisting in the simulation of the slurry flow by an Eulerian–Lagrangian two-phase model followed by the application of an empirical erosion correlation to estimate the loss of material produced by each particle-wall impact. One of the main assumptions of this approach is that the solids are treated as massive point particles, even if, from a theoretical point of view, this approximation may be too simplistic, as it requires the particle size to be infinitesimal. The objective of the present study was, primarily, to assess how the point–particle treatment of the dispersed phase may affect the accuracy of CFD-based erosion prediction models. Based on these findings, numerical strategies were proposed in order to correct for the induced error without the need of resorting to a fully-resolved description of the slurry flow, which would not be affordable in practical applications due to its excessive computational burden. As a first step, reference was made to the benchmark case of slurry abrasive jet impingement test. The obtained results will open the way for addressing more complex flows in future research.

Polymer@silica composites with tunable outer and inner surface properties: a platform for aqueous asymmetric transfer hydrogenation

2015 ◽  
Vol 17 (3) ◽  
pp. 1899-1906 ◽  
Author(s):  
Xiaoming Zhang ◽  
Yaopeng Zhao ◽  
Juan Peng ◽  
Qihua Yang
Keyword(s):  
Aqueous Medium ◽  
Surface Properties ◽  
Transfer Hydrogenation ◽  
Asymmetric Transfer Hydrogenation ◽  
Inner Surface

The polymer@silica composites with tunable outer and inner surface properties could efficiently catalyze the asymmetric transfer hydrogenation (ATH) of ketones in aqueous medium.

Interaction of Reactive Species Obtained by G-D Silane Decomposition with Si(111) and a-Si:H Surfaces

1987 ◽  
Vol 95 ◽  
Author(s):  
S. A. Cruz ◽  
V. M. Mendez-Rosales
Keyword(s):  
Potential Barrier ◽  
Surface Potential ◽  
Reactive Species ◽  
Interatomic Potentials ◽  
Average Surface ◽  
Thomas Fermi ◽  
First Case ◽  
Crystalline Surface ◽  
Total Interaction

AbstractWe calculate the average surface potential barrier for incorporation of H, Si, SiHb (n=1–4) into films of a-Si:H as well as crystalline Si(111) surfaces. In the first case a local amorphous configuration for the surface is employed through a representative cluster(Si29 H1 0 ) forming 5, 6, 7 Si atom rings. For the crystalline surface, several layers of Si atoms are considered. Pairwise superposition of combined Morse and Thomas-Fermi-Moliére interatomic potentials is assumed for the total interaction between the incoming species and the surface.

Development of Cup Inner Surface Smoothing Process by Ironing

2013 ◽  
Vol 535-536 ◽  
pp. 263-266 ◽  
Author(s):  
Atsushi Tanaka ◽  
Zhi Gang Wang ◽  
Nobuyuki Hibi
Keyword(s):  
Surface Properties ◽  
Surface Quality ◽  
Surface Property ◽  
Surface Smoothing ◽  
Multi Stage ◽  
Inner Surface ◽  
Smoothing Process ◽  
Normal Method ◽  
Punch Shape

Ironing process is a normal method to improve the surface quality and thickness precision of a drawn cup. Multi-stage processes that combined drawing and ironing, have been developed to obtain the cups with a each surface quality. However, the ironing process is generally used to outside of the drawn cup, and the trial to improve the inside surface property is not carried out very much. The purpose of this study is to clarify the effect of ironing process on the improvement of the surface quality of multi-stage drawn cup. The effects of the ironing reduction, lubricants and punch shape on the improvement of the inner surface properties are investigated by using a series of experiment. It is found that the inner ironing process is effective to improve the inner surface properties of a drawn cup.

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